Electric drive system for an electric bicycle

Abstract

Drive system (10) for an electric bicycle (1), comprising a generator (12) driven by a pedal movement; a hub motor (14) for driving a wheel (2, 4), in particular a rear wheel (2) or a front wheel (4) of the electric bicycle; an electrical connection (16) between the generator (12) and hub motor (14), so that the electrical energy generated by the generator can be supplied directly or indirectly to the hub motor (14).

Description

Technical area

[0001] The invention relates to an electric drive system for an electric bicycle (pedelec) and an electric bicycle with such an electric drive system. State of the art

[0002] Electric bicycles (also known as pedelecs) have established themselves as important components of modern urban mobility in recent years. Unlike e-bikes, which can run purely electrically without pedal assistance, electric bicycles (pedelecs) only assist the rider while pedaling up to a speed of, for example, 25 km / h. So-called S-pedelecs provide assistance up to, for example, 45 km / h and are legally considered mopeds in Germany. Technological advances in batteries, motors, and control electronics have significantly increased the performance and range of these electric bicycles, but challenges remain, particularly in the area of ​​drive systems.

[0003] Common drive systems can essentially be divided into three categories: front-wheel drive, rear-wheel drive and mid-engine.

[0004] With front-wheel drive, the motor, an electric motor, is located in the hub of the front wheel. This design is inexpensive and relatively easy to install, but is usually only found in inexpensive models. Disadvantages include an unfamiliar ride, especially on wet or loose surfaces, as well as unfavorable weight distribution.

[0005] With rear-wheel drive, the electric motor is located in the rear wheel hub. This option offers better traction and a more natural ride, as the drive power comes from the rear – similar to a conventional bicycle. Rear-wheel drives are particularly popular with sporty electric bikes and speed pedelecs. However, integrating hub gears is technically complex, so derailleur gears are usually used.

[0006] Currently, the most common type is the so-called mid-drive motor, located at the bottom bracket. Advantages include a low center of gravity, good weight distribution, and direct power transmission to the rear wheel via a chain or belt. This allows the use of conventional mechanical gears (e.g., derailleur gears or hub gears). In addition, mid-drive motors allow for sensitive sensor technology that evaluates torque, cadence, and speed, for example, to optimally adjust the rider's electrical assistance.

[0007] Despite established drive systems, challenges still exist in the field of drive systems for electric bicycles. For example, drive systems with a mid-drive motor often exhibit high levels of wear, as the mid-drive motor transmits its power directly via the bicycle chain or belt, thus contributing to increased chain and sprocket wear. Especially with high levels of assistance and poor maintenance, components must be replaced frequently, which increases operating costs. Furthermore, the assistance or motor control system is often inadequately tailored to the rider's pedaling power. Problems such as jerky starts or delays in assistance are recurring. Disclosure of the invention

[0008] The invention is therefore based on the object of at least partially eliminating the above disadvantages and of providing an improved drive system for an electric bicycle (Pedelec) and an electric bicycle with such an electric drive system.

[0009] This object is achieved by a drive system according to claim 1 and by an electric bicycle according to claim 16. Further aspects of the invention are mentioned in the following description and the dependent claims.

[0010] In particular, the problem is solved by a drive system for an electric bicycle. The drive system comprises a generator driven by pedaling, a hub motor for driving a wheel of the electric bicycle, and an electrical connection between the generator and the hub motor, so that the electrical energy generated by the generator can be supplied directly or indirectly to the hub motor.

[0011] The hub motor can drive at least one rear wheel and / or at least one front wheel. Furthermore, the drive system can be implemented in various types of electric bicycles, including conventional electric bicycles, cargo bikes, recumbent bikes, tandems, tricycles, rickshaws, or other multi-track bicycles. The flexibility of the system also allows for its use on specialty bicycles such as mountain bikes, racing bikes, or folding bikes.

[0012] The generator is typically located on or integrated into the bottom bracket. In particular, the bottom bracket can be coupled to the generator in such a way that no chain (or belt) is provided between the bottom bracket and the generator. However, as described below, the provision of a transmission is possible. The generator is driven by the rider's pedaling motion via the pedals (e.g., foot or hand pedals) and converts the mechanical energy of the pedaling motion into electrical energy. This conversion occurs continuously during pedaling, with the electrical energy generated being proportional to the applied pedaling power.

[0013] The electrical connection between the generator and hub motor can enable direct or indirect energy transfer. With direct energy transfer, the electrical energy generated by the generator is fed directly to the hub motor without intermediate storage. This enables particularly efficient energy transfer with minimal losses and a direct connection between pedaling power and motor assistance. With indirect energy transfer, the electrical energy is first stored in an intermediate storage device such as an accumulator, a capacitor, or other electrical energy storage device and then fed to the hub motor. This indirect energy transfer enables temporally decoupled energy transfer and advanced functions such as energy buffering, recuperation, and purely electric driving without pedal assistance.

[0014] In particular, the drive system enables electrical energy transfer, without direct mechanical transmission, between the bottom bracket and the wheel, thereby reducing wear and increasing efficiency.

[0015] According to one aspect, the drive system further comprises at least one accumulator, wherein the accumulator is electrically connected to the hub motor and / or the generator, so that electrical energy generated by the generator can be stored in the accumulator and / or electrical energy stored in the accumulator can be supplied to the hub motor. This enables flexible energy management that supports both direct energy transfer and energy storage for extended range.

[0016] The battery can comprise various battery technologies, including lithium-ion batteries, lithium polymer batteries, lithium iron phosphate batteries (LiFePO4), or solid-state batteries. These different battery types offer different advantages in terms of energy density, service life, safety, and charging speed, allowing the drive system to be adapted to different application requirements.

[0017] For example, the electrical energy generated by the generator (in the range from 0% to 100%) can be supplied to the hub motor or the accumulator in various ways: First variant (accumulator-based energy transfer): The energy generated by the generator is transferred entirely to the accumulator (or another electrical storage device) and stored there. The hub motor is powered exclusively by the accumulator or storage device. Optionally, the hub motor can recover kinetic energy and transfer it to the accumulator or storage device. This variant offers the advantage of temporally decoupled energy transfer, enables purely electric riding without pedal assistance, and ensures a consistent energy supply to the hub motor regardless of fluctuations in pedaling power.

[0018] Second variant (direct energy transfer): The energy generated by the generator is fed directly to the hub motor, without intermediate storage. The hub motor is also powered by the accumulator (or an intermediate electrical storage device) to achieve the required total power. Regenerative braking can also be optionally implemented here. This variant offers the advantage of higher efficiency by avoiding storage losses, a direct coupling between pedaling power and motor assistance, and particularly efficient energy transfer.

[0019] Third variant (hybrid energy transfer): The energy generated by the generator is split between the hub motor and the accumulator (or an intermediate electrical storage device). Preferably, only excess energy is sent to the accumulator (or intermediate storage device) for storage, while a basic requirement is fed directly to the hub motor. The hub motor is additionally powered from the accumulator (or intermediate storage device) when needed. Regenerative braking is also optionally available here. This variant combines the advantages of both previous approaches: optimal efficiency through direct energy transfer with simultaneous flexibility through energy storage, intelligent energy management, and maximum system efficiency.

[0020] According to one aspect, the hub motor is configured to recover kinetic energy and supply recuperatively generated electrical energy to the battery. This increases energy efficiency by recovering braking energy and extends the range of the electric bicycle.

[0021] Regenerative braking typically occurs during braking, downhill riding, and / or coasting, with the electric bike's kinetic energy being converted into electrical energy and fed into the battery. The degree of regenerative braking can be adjustable. For example, the degree of regenerative braking can be set via a control unit or a speed selector, which can be located on the handlebars of the electric bike. Using the degree of regenerative braking, the rider can individually adapt the braking characteristics and / or energy recovery to their riding style.

[0022] According to one aspect, the generator is configured to adjust pedal resistance. Pedal resistance is the resistance the rider must overcome while pedaling. The higher the resistance, the greater the force (or torque) required while pedaling. The power delivered to the generator is calculated using the following formula: Power(P)=Torque(M)×Angular velocity (ω), where the angular velocity is ω = 2π × cadence (f).

[0023] By adjusting the pedal resistance, the generator can be optimally tuned to different riding situations and rider preferences. Furthermore, adjusting the pedal resistance leads to optimal energy generation at different cadences.

[0024] In one aspect, the generator comprises a gear system arranged between the bottom bracket and a rotor of the generator. The gear system can be configured as a spur gear system, planetary gear system, bevel gear system, worm gear system, manual gear system, or automatic gear system. Manual gear systems allow manual adjustment of the gear ratio to different riding situations, while automatic transmission systems automatically optimize the gear ratio according to the cadence and load. This allows the riding resistance to be individually adjusted, achieving optimal energy generation at different cadence levels.

[0025] In a further aspect, the generator comprises at least one radially movable permanent magnet and / or at least one excitation winding. The radial adjustment of the at least one permanent magnet causes a change in the magnetic resistance. The adjustment can be controlled electronically or manually. With the change in the magnetic resistance, the tread resistance also changes. If an excitation winding is provided, the magnetic field can be generated electrically, which enables particularly good controllability. Thus, the tread resistance can be adjusted particularly easily. In one aspect, the generator can be designed, for example, as a permanently excited synchronous generator.

[0026] According to one aspect, the drive system further comprises a control unit, wherein the control unit is configured to regulate or control the power output of the generator and / or the hub motor. This can be done automatically and / or continuously.

[0027] In particular, the control unit can control or regulate the power output of the generator to the hub motor and / or the power output of the generator to the accumulator. Furthermore, the control unit can control or regulate the power output of the hub motor to the driven wheel and / or the power output of the hub motor to the accumulator (regeneration).

[0028] In particular, the regulation or control of the power output of the generator and / or the hub motor can be carried out taking into account at least one of the following parameters: Pedal torque, cadence, pedaling power, riding speed, acceleration, terrain gradient, headwind, gear selection, braking status, selected support level, battery voltage, and / or battery charge level. This enables adaptive control of the drive system for optimal riding characteristics and energy efficiency.

[0029] The assistance levels define the relationship between the electrical energy generated by the generator and the power delivered by the hub motor. For example, five assistance levels can be provided: 0% assistance, 20% assistance, 40% assistance, 60% assistance, 80% assistance, and 100% assistance.

[0030] For example, at a support level of 20%, the power generated by the generator can correspond to 80% of the total power delivered by the hub motor to the wheel, with the remaining 20% ​​provided by the battery. If a motor power of 500 W is desired, 400 W would come from the generator and 100 W from the battery.

[0031] According to one aspect, the drive system comprises at least one sensor for detecting various parameters such as pedaling torque, cadence, travel speed, acceleration, terrain gradient, headwind, gear selection, braking status, battery voltage, and / or battery charge level, wherein the at least one sensor is optionally connected to the control unit for communication. This enables precise detection of the riding situation, which serves as the basis for intelligent control.

[0032] The sensors can comprise various technologies and can be positioned at different locations on the electric bicycle or drive system, e.g.: strain gauges or torque sensors on the bottom bracket to record the pedaling torque; Hall sensors or optical encoders on the generator to measure the cadence; wheel speed sensors or GPS modules to measure speed; acceleration sensors (accelerometers) in / on the frame of the electric bicycle or the control unit; inclination sensors (gyroscopes) to record the gradient of the terrain; pressure sensors or anemometers for measuring headwind; position sensors on the gearshift for gear selection; microswitches or Hall sensors on the brake levers to record the braking status; and voltage and current sensors on the battery to monitor the voltage and / or charge level.

[0033] According to one aspect, the control unit is configured to automatically adjust the assistance level, in particular depending on the terrain gradient, headwind, and / or pedaling power. This reduces the operator effort for the rider and automatically optimizes the riding characteristics according to the current riding conditions.

[0034] According to one aspect, the control unit is configured to control the hub motor such that it rotates at a target speed and / or drives the electric bicycle at a target speed. This enables precise speed control, ensuring constant riding speeds and improved riding comfort. The target speed can be specified, for example, via a speed selection element (e.g., a throttle lever or a twist grip) on the handlebars of the electric bicycle. At a support level of 100%, the drive system can drive the electric bicycle independently, without the rider having to pedal or generating electrical energy from the generator.

[0035] According to one aspect, the control unit is configured to switch between different operating modes, wherein the operating modes include at least a pedelec mode and an e-bike mode. In pedelec mode, the electrical energy generated by the generator controls the power output of the hub motor depending on the pedaling power (depending on the selected assistance level). In e-bike mode, the speed of the electric bicycle can be controlled independently of the pedaling power via the speed selection element. This offers the rider maximum flexibility between pedal-assisted and purely electric riding.

[0036] According to one aspect, the hub motor is a brushless DC motor. Furthermore, the hub motor can include a transmission, particularly a manual or automatic transmission. This achieves high efficiency, low maintenance, and optimal power transmission at various speeds.

[0037] Another aspect of the hub motor is its continuously variable power control. This allows for precise and consistent adjustment of the motor power for optimal riding comfort without jerky transitions.

[0038] In addition, the drive system can include a bottom bracket, which can be integrated with the generator, particularly as an encapsulated unit. This results in a compact design, reduced maintenance requirements, and improved protection against environmental influences.

[0039] According to one aspect, the drive system further comprises a display unit and / or an operating unit. The display unit can be configured to graphically display system information such as current power flow, energy consumption, and battery charge level. The operating unit can be configured to allow a user to select a support level. This enables user-friendly operation and monitoring of the system. In particular, the display unit and the operating unit can be configured as an integrated display-operating unit.

[0040] According to a further aspect, the drive system comprises at least one data interface for wireless communication with at least one mobile device and / or a body-worn sensor, in particular a physiological sensor. The data interface can communicate with various mobile devices, in particular smartphones, smartwatches, fitness trackers, or bike computers. Body-worn sensors include, for example, heart rate monitors (chest straps), smartwatches with pulse measurement, activity trackers, blood pressure monitors, or respiratory rate sensors. The wireless connection enables extended functions such as smartphone integration for navigation and route planning, fitness tracking with calorie consumption and training analysis, remote monitoring of the bicycle for theft protection, automatic trip log management, maintenance reminders based on usage data, and the integration of biometric data for personalized assistance profiles.

[0041] The integration of physiological sensors, such as heart rate monitors, allows the hub motor's assistance to be adapted to physiological parameters. This prevents the rider from overexerting themselves and / or ensures that the rider completes an ideal workout (e.g., target performance).

[0042] According to one aspect, the drive system further comprises at least one speed selection element, wherein the speed selection element is configured to convert a user input into a target speed. This enables intuitive speed control similar to a throttle lever, which is particularly advantageous in e-bike mode. Furthermore, the speed selection element can be configured to set a recuperation level.

[0043] The object is further achieved by an electric bicycle comprising pedals (hand or foot pedals) and a drive system, wherein the drive system is designed as described above. According to this aspect, the generator of the drive system can be driven by the pedals via a pedaling motion. The advantages described above can be realized with this electric bicycle. Short description of the characters

[0044] The invention is explained in more detail below with reference to the accompanying figures. Fig. 1 a conventional electric bicycle (pedelec) with a mid-engine according to the state of the art; Fig. 2 an electric bicycle with a drive system according to the invention; Fig. 3 a detailed view of a handlebar of an electric bicycle, Fig. 4 a block diagram of a drive system with indirect energy transfer between generator and hub motor; Fig. 5 a block diagram of a drive system for direct energy transfer between generator and hub motor, and Fig. Figure 6 shows a block diagram of a drive system with hybrid energy transfer between generator, accumulator and hub motor. Detailed character description

[0045] Fig. Figure 1 shows a conventional electric bicycle 1 with a mid-engine according to the prior art. The electric bicycle 1 comprises a frame 5, a rear wheel 2, and a front wheel 4. A saddle 30 and a handlebar 32 are arranged on the frame 5. The handlebar 32 houses a display unit 34 for displaying riding data and optional controls for controlling the electric bicycle.

[0046] This conventional electric bicycle includes a mid-drive motor 26 positioned at the bottom bracket 24. The mid-drive motor 26 transmits its drive power mechanically to the rear wheel 2 via a chain 28. The pedals 22 are directly connected to the bottom bracket 24 and allow the rider to contribute mechanical energy to the system in addition to the electrical assistance.

[0047] A battery 18 is integrated into the frame 5 and supplies the mid-drive motor 26 with electrical energy. Mechanical power transmission occurs exclusively via the chain 28, whereby both the mechanical energy applied by the rider via the pedals 22 and the drive force generated by the mid-drive motor 26 are transferred jointly to the rear wheel 2. Instead of the chain, a belt, for example, can also be used.

[0048] This conventional configuration leads to the disadvantages already described: The direct mechanical power transmission via the 28-inch chain causes increased wear on the chain and sprockets (or belts), especially with strong electric assistance. Furthermore, energy transfer is less efficient due to mechanical friction losses in the drive chain. The direct coupling between pedaling and wheel drive also limits the flexibility in implementing different operating modes.

[0049] Fig. 2 shows an electric bicycle 1 with a drive system 10 according to the invention. In contrast to the Fig. Unlike the conventional system shown in Figure 1, this embodiment includes a generator 12 that can be driven by pedaling. For this purpose, the generator 12 is arranged at the bottom bracket 24. Furthermore, the drive system includes a hub motor 14 in the rear wheel 2. Alternatively, the hub motor can also be arranged in the front wheel 4. The generator 12 is connected to the hub motor 14 via the electrical connection 16, whereby the electrical energy generated by the pedaling movement of the pedals 22 can be supplied to the hub motor 14.

[0050] The accumulator 18 is held on the frame 5 or integrated into the frame 5 and is connected via electrical connections to both the generator 12 and the hub motor 14. It is understood that the accumulator 18 can also be located elsewhere on the electric bicycle 1. The connection between the generator 12 and the hub motor 14 can be made directly or via the accumulator 18, as described with reference to Fig. 4 to 6. The provision of an accumulator 18 enables both the storage of the energy generated by the generator 12 and the supply of the hub motor 14 with stored energy.

[0051] Sensors 42, 44, and 46 can be arranged at various positions on the drive system 10. For example, a sensor 42 can be provided on the accumulator 18 to monitor the voltage and / or charge level of the accumulator 18. Furthermore, a sensor 44 can be arranged on the bottom bracket 24 (or on the generator 12) to detect torque and / or cadence. Furthermore, a sensor 46 can be provided on the hub motor 14, for example, to measure speed. It is understood that other or additional sensors, such as an acceleration sensor or even physiological sensors, can be provided. The data acquired by the sensor(s) can be used to control and / or regulate the drive system.

[0052] A control unit (in Fig. 2 not shown) coordinates the drive system 10 and is available, for example, via communication connections 17 (see Fig. 4-6) with the generator 12, the hub motor 14 and optionally with the accumulator 18.

[0053] For example, a display unit 34 and / or a control unit is arranged on the handlebar 32, which allows the rider to monitor and control the drive system 10 or the electric bicycle 1. For example, a support level and / or an operating mode can be selected via the control unit.

[0054] The drive system 10 enables the energy generated during pedaling to be transferred in electrical form to the hub motor. There, the energy is converted back into kinetic energy to drive the rear wheel 2. This drive system 10 eliminates the need for a mechanical transmission between the bottom bracket 24 and the rear wheel 2. Therefore, no chain, no belt, and no other mechanical transmission elements are required, reducing wear and increasing efficiency. Furthermore, the pedaling motion is decoupled from the wheel drive. This decoupling of pedaling motion and wheel drive enables extended operating modes such as recuperation, charging the battery using the generator, and / or purely electric driving.

[0055] Fig. Figure 3 shows a detailed view of an exemplary handlebar 32 of an electric bicycle with the control elements 34, 36, 38, 40 of the drive system 10 according to the invention. A control unit 36, for example, is arranged on the left handlebar grip. This can comprise touch switches or other control units and serves, for example, to select a support level and / or an operating mode.

[0056] The display unit 34 can be integrated into the control unit 36 ​​and can be configured to show the rider important system information such as speed, range, battery level and / or selected support level.

[0057] The right handlebar grip features an optional speed selector 38, designed here as a twist grip. It can be used both for speed control, in particular for setting a target speed, and for adjusting the recuperation level.

[0058] The brake levers 40 are located on both sides of the handlebar 32 and can be equipped with sensors to detect the braking status. This ergonomic arrangement of the controls allows intuitive control of the drive system while riding, without the rider having to take their hands off the handlebar. The integration of all controls on the handlebar 32 contributes to the system's user-friendliness and safety.

[0059] The Fig. Figures 4 to 6 show various block diagrams of possible drive systems. The block diagrams differ primarily in the type of energy transfer between generator 12 and hub motor 14, as well as between generator 12 and accumulator 18. The energy transfer between accumulator 18 and hub motor 14 is identical in all block diagrams shown. Energy can always be supplied to hub motor 14 from accumulator 18. Regeneration is also optionally implemented, allowing hub motor 14 to return energy to accumulator 18 (e.g., during braking or when driving downhill).

[0060] In particular Fig. Figure 4 shows a block diagram of a drive system 10 with indirect energy transfer between generator 12 and hub motor 14. In this configuration, the electrical energy generated by generator 12 is entirely transmitted via electrical connection 16 to accumulator 18 and stored there. The hub motor 14 is powered exclusively by accumulator 18 via a separate electrical connection 16.

[0061] The control unit 20 coordinates the energy flow between the components generator 12, hub motor 14 and accumulator 18 and is connected to generator 12, accumulator 18 and hub motor 14 via communication links 17.

[0062] For example, this drive system can be operated in pedelec mode or e-bike mode. In pedelec mode, the electrical energy generated by generator 12 is fed to accumulator 18. Control unit 20 controls the energy output from the accumulator to hub motor 14 based on the energy (or power) generated at the generator. If more energy is generated at generator 12 than is needed, for example, to reach a permissible maximum speed, the excess energy can be used to charge accumulator 18. In e-bike mode, the speed of electric bicycle 1 can be controlled via the speed selection element independently of pedaling power. This means the rider does not have to pedal. If they do pedal, the energy generated at generator 12 can be temporarily stored in accumulator 18.

[0063] A data interface 21 enables wireless communication with external devices, such as mobile devices or other sensors, in particular physiological and / or body-worn sensors. This data interface can be a Bluetooth interface, an ANT+ interface, a Zigbee interface, and / or the like.

[0064] The Fig. The indirect energy transfer shown schematically in Figure 4 offers the advantage of temporally decoupled energy transfer, enabling purely electric riding without pedal assistance. Furthermore, the accumulator 18 acts as a buffer storage device, ensuring a consistent energy supply to the hub motor 14, regardless of fluctuations in pedaling power.

[0065] Fig. 5 shows a block diagram of a drive system 10 with direct energy transfer between generator 12 and hub motor 14. In contrast to Fig. 4, the electrical energy generated by the generator 12 is fed directly to the hub motor 14 via the electrical connection 16, without intermediate storage in the accumulator 18. The accumulator 18 serves as an additional energy source and feeds the hub motor 14 via a separate electrical connection 16 in order to achieve the required total power.

[0066] The control unit 20 regulates the power distribution between energy generated directly by the generator and energy drawn from the accumulator 18, according to riding requirements, such as operating mode and / or assistance level. This direct energy transfer offers greater efficiency by avoiding storage losses and enables a direct coupling between pedaling power and motor assistance. The rider thus feels an immediate response from the system to their pedaling movement, resulting in a more natural riding experience. The direct energy transfer enables the operating modes described above, Pedelec mode and E-Bike mode. However, it is not possible to charge the accumulator 18 directly via the generator 12. Charging via the hub motor 14, however, is possible.

[0067] Fig. Figure 6 shows a block diagram of a drive system 10 with hybrid energy transfer between generator 12, accumulator 18 and hub motor 14. This configuration combines the advantages of the Fig. 4 and Fig. 5, by dividing the electrical energy generated by the generator 12 between the hub motor 14 and the accumulator 18. The electrical connections 16 enable both the direct transfer of energy from the generator 12 to the hub motor 14 and the storage of excess energy in the accumulator 18.

[0068] The control unit 20 is configured to control or regulate the energy distribution between the components generator 12, hub motor 14, and accumulator 18. For example, a base demand is supplied directly from the generator 12 to the hub motor 14, while surplus energy is stored in the accumulator 18. When power demand increases, additional energy from the accumulator 18 is supplied to the hub motor 14. This hybrid energy transfer maximizes system efficiency through optimal efficiency with direct energy transfer while simultaneously offering the flexibility of energy storage for advanced functions such as recuperation and various operating modes, such as pedelec mode and e-bike mode.

[0069] Examples of energy distribution are shown in tables below.

[0070] Table 1 shows an example energy distribution for a drive system with indirect energy transfer, with the rider pedaling at a constant 100 watts. Losses such as friction losses, transmission losses, storage losses, and / or charging losses are not taken into account. Table 2 shows an example energy distribution for a drive system with indirect energy transfer, where the hub motor delivers a constant 300 watts. The required pedaling power, depending on the assistance level, which the rider or generator must provide, varies accordingly. Losses such as friction losses, transmission losses, storage losses, and / or charging losses are not taken into account. List of reference symbols 1 electric bike 2 rear wheel 4 front wheel 5 frames 10 Drive system 12 Generator 14 hub motor 16 electrical connection 17 Communication connection 18 Accumulator 20 Control unit 21 Data interface 22 Pedal 24 bottom bracket 26 mid-engine 28 chain 30 saddle 32 handlebars 34 display unit 36 Control unit 38 Speed ​​selection element 40 brake levers 42 Sensor 44 Sensor 46 Sensor

Claims

[1] Drive system (10) for an electric bicycle (1), comprising a generator (12) driven by a pedal movement; a hub motor (14) for driving a wheel (2, 4), in particular a rear wheel (2) or a front wheel (4) of the electric bicycle; an electrical connection (16) between the generator (12) and hub motor (14), so that the electrical energy generated by the generator can be supplied directly or indirectly to the hub motor (14). [2] Drive system (10) according to claim 1, further comprising at least one accumulator (18), wherein the accumulator is electrically connected to the hub motor (14) and / or the generator (12) so that electrical energy generated by the generator (12) can be stored in the accumulator (18), and / or electrical energy stored in the accumulator (18) can be supplied to the hub motor (14). [3] Drive system (10) according to claim 2, wherein the hub motor (14) is configured to recuperate kinetic energy and to supply recuperatively generated electrical energy to the accumulator (18). [4] Drive system (10) according to one of claims 1 to 3, wherein the generator (12) is configured to adjust a pedal resistance, and wherein the generator (12) comprises in particular one of the following: - a gear arranged between a bottom bracket (24) and a rotor of the generator; - at least one radially movable permanent magnet, and / or - at least one excitation winding. [5] Drive system (10) according to one of claims 1 to 4, further comprising a control unit (20), wherein the control unit (20) is designed to regulate or control the power output of the generator (12) and / or the hub motor (14), taking into account at least one of the following parameters: Pedal torque, cadence, pedaling performance, Driving speed, acceleration terrain gradient, Headwind, gear selection, braking condition, selected support level, Battery voltage, and / or Battery level. [6] Drive system (10) according to one of claims 1 to 5, wherein the drive system comprises at least one sensor (42, 44, 46), and wherein the at least one sensor is configured to detect one of the following parameters: Pedal torque, cadence, pedaling performance, Driving speed, acceleration terrain gradient, Headwind, gear selection, braking condition, Battery voltage, and / or Battery charge level is set up, whereby the at least one sensor is optionally in communication with the control unit (20). [7] Drive system (10) according to one of claims 1 to 6, wherein the control unit (20) is configured to automatically adjust the support level, in particular depending on the gradient of the terrain, headwind and / or pedaling power. [8] Drive system (10) according to one of claims 1 to 7, wherein the control unit (20) is configured to control the hub motor (14) such that it rotates at a target speed and / or drives the electric bicycle (1) at a target speed. [9] Drive system (10) according to one of claims 1 to 8, wherein the control unit (20) is arranged to switch between different operating modes, the operating modes comprising at least: a Pedelec mode in which the electrical energy generated by the generator (12) controls the power output of the hub motor (14) depending on the pedaling power; an e-bike mode in which the speed of the electric bicycle (1) can be controlled independently of the pedaling power via a speed selection element (38). [10] Drive system (10) according to one of claims 1 to 9, wherein the hub motor (14) is a brushless DC motor and / or comprises a transmission, in particular a manual or automatic transmission. [11] Drive system (10) according to one of claims 1 to 10, wherein the hub motor (14) has a continuously variable power control. [12] Drive system (10) according to one of claims 1 to 11, further comprising a bottom bracket (24), wherein the bottom bracket (24) is integrated with the generator (12), in particular as an encapsulated unit. [13] Drive system (10) according to one of claims 1 to 12, further comprising a display unit (34) and / or an operating unit (36), wherein the display unit (34) is configured to graphically display system information, wherein the system information comprises at least one of the following: a current power flow, energy consumption, a charge state of the accumulator (18), and wherein the control unit (36) is designed to enable a user to select a support level. [14] Drive system (10) according to one of claims 1 to 13, further comprising at least one data interface (21) for wireless communication with at least one mobile terminal and / or a body-worn sensor. [15] Drive system (10) according to one of claims 1 to 14, further comprising at least one speed selection element (38), wherein the speed selection element (38) is configured to convert a user input into a desired speed. [16] Electric bicycle (1), comprising pedals (22) and a drive system (10) according to one of claims 1 to 15, wherein the generator (12) of the drive system (10) can be driven by means of the pedals (22) via a pedaling movement.

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